Chair-iron



H; e. HUNN.

CHAIR IRON. 7 APPLICATION FILED Nov. 4; 1920.

1,3683%. Patented Feb. 15,1921.

1g 7 0/114 if; l w v CHAIR-IRON.

weaves.

Application filed. November 4, 1920.

To all whom it may concern:

Be it known that I, HOWARD G. HUNN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and usefnl Improvements in Chair-Irons, of which the following is a specification.

My invention relates to improvements in chair irons, particularly of the type in which the seat is vertically adjustable, and the back of the chair carrying the back rest is tiltable as Well as adjustable vertically and toward and from the seat. This type of chair iron is well exemplified in United States Letters Patent No. 1,044,530 granted to me on November 19, 1912. V

In the patent referred to, I have disclosed means for holding the back rest in adjusted position and the present invention is primarily directed to an improvement of such mechanism. The means of Patent 1,044,530 for holding the back rest in adjusted position includes toothed collars coactingwith toothed clamping jaws, and while this construction is an efficient one in many respects, it was found that in course of time the teeth of the collars and clamping jaws stripped or were injured and'that consequently the clamping action was less effective after long use of the iron than it was when the iron was new. The principal object of the present invention is to obviate this defect and to provide a form of clamp which is simple in construction and'action and will indefinitely retain its original clamping efficiency.

The present invention also includes a modification in the means for supporting one end of the spring which controls the tilting action of the chair seat, such modified means being desirable from a manufacturing standpoint because of economy and simplicity of construction.

My invention as applied to what is generally termed a stenographers chair is illustrated in the accompanying drawing, wherein Figure 1 is a side elevation,- with parts broken away, of such a chair; Fig. 2 is a horizontal sectional View on the line 2-2 of Fig. 1; Fig. 3 is a similar view on the line 33 of Fig. 2; and Fig. 4 is a similar view on the line 4-4 of Fig. 1.

The chair illustrated in the drawing comprises the legs 10'held together by a hub 11 in which the spindle 12 is revolubly supported. Movable longitudinally of the spindle 12 is a casing 13 which, with the di- Specification of Letters Patent.

Patented Feb. 15, 1921.

Serial No. 421,639.

vergent opposed arms 14, constitutes the carrier for the seat 15*. The casing 13 has the extended plates 15 and 16 provided with ahned orifices to receive the adjusting screw 17 the lower end of which is retained against yertical displacement in a collar 18 embracing the spindle 12. The screw carries rigidly a hand wheel 19, and the construction is such that by revolving the screw 17 through the intermediary of the hand wheel 19 the casing 13 and the seat carried thereby may be raised and lowered on the spindle 12. The mechanism thus generally described is substantially similar to that disclosed in my earlier patent.

Extending rearwardly from the seat carrler casing 13 is a yoke 20, the rear face 20 of which is arched and'externally toothed or serrated. Traversing the yoke, arms 20 near their rear ends is a pin 21 on which is pivotally mounted the pair of clamping jaws 22 and 23, each of'the latter having its rear wall inturned or hooked as at 22 for the purpose of engaging the outer ends of the arched or substantially concavo-convex plate 24 carried at the lower end of the back member 25 to the upper part of which the back rest 26 is attached. It will be understood that under certain conditions the clamping jaws are freely movable about the pin 21 as a pivot.

Operable within the clamping jaws are wedge members 27 and 28 of special construction for engaging both the face 20 of the yoke 20 and the rear faces of the arched plate 24. The wedge 27 has an extended boss 27- which is adapted to be moved in an opening 22 in the lateral wall of the jaw 22. The boss 2" and the body portion of the wedge 27 in line therewith are provided with an internal threaded bore designed to be engaged by the threaded portion 30 of a stem 31 carrying a hand wheel 32 at one end for rotating the stem.

The wedge 28 has an extended boss 28 adapted to be moved in an opening 23* in the lateral wall of the jaw 23. The boss 28 and the body portion ofthe wedge 28 in line therewith are provided with a smooth inter nal bore to receive the smooth portion 33 of the stem 31. The portions 30 and 33 of the stem are of smaller diameter than the remainder thereof, thus forming a shoulder adjacent the outer end of the boss 28 Extending forwardly from the boss 27 is a wedge arm 27 adapted to engage the arched and serrated face 20*, and extending rearwardly from the hub 27 is a second arm 2'7 to engage the rear inclined face of the plate 24. The engaging faces of the arms 27 and 27 Z are chamfered or inclined to the same degree as the inclination of the surfaces with which they respectively coact.

The boss 28 likewise has forwardly and rearwardly extending arms28 and 28 for V engagement, respectively, with the 'yoke face 7 20 and the plate 24. Extending'through the stem 3-1 betweenthe threaded and smooth portions thereof is a pin 35'to act as a'spac'e'r between the wedges.

The wed'ging mechanism, above described, is provided to control the adjustment of the back 25, both'in an up and down direction, and toward and away from the seat It 7 operates substantially as follows Withjthe parts in the position of Fig. '4: the wedges tightly engage the opposed faces of the parts and 24- and the plates 24 aswell as the clamping jaws 22-and 23 are firmly held.

If, now, it be desired to vary the adjustment of the back25 vby changing its vertical pos tion or its inclination, or both, the hand wheel 32 is revolved in the proper direction to cause the threaded portion 30of the'stem a to move the wedgearm 27 -outwa'rdly asufii- 80 cient distance to release the clamping acti'o'n of the hooks-22 on the plate24, and also 'to release the wedging action of the'wedg'e arms in relation to the surface 20 'and t e 'inner'inclined faces of-the plate 24'. In this condition of the parts the plate 24 may be moved up or down to obtain the desired vertical adjustment thereof, and the clamping jaws 22 and 23, with their appurtenant parts, maybe moved pivotally about the pin 21 to, obtain the desired inclination of the back 25 (or back rest 26). Thereupon', in

orderto lock the'parts inadjusted position, 7 it is "merely necessary to rotate the handwheel- 32 in a direction opposite that in which'it was first rotated, and the result will be to draw the wedges toward each other whereby the wedge arms 27 and 28 vfirmly engage against the arched face 2O while the wedge arms 27 and 28 will tend to force the arched back plate 24 against the hooked ends 22, and the shoulder 34 will engage the outer end ofthe boss 28*; the sum total of these several factors being that the arms 22 and 23 are locked against rotation andthe plate 24, with the back and back rest carried thereby, is locked against vertical displacement. It will be apparent from the foregoing explanation thatmanipulation of but a single member, via, the hand wheel 32 is necessary in effecting both kinds of adjustment of the back rest. stated in this connection that the wedge faces of the arms27 and 28 are preferably serrated or ridged to correspond with the on the. spring.

It should be ,7

serrations of theface 20 to thereby secure an effective interlock of these parts. 7

The yoke arms 20, which constitute the carrier for the back 25, have downwardly" curved extensions 14, and passing through the lower ends of these extensions and bearing in the casing 13 is a pin 36 which serves as a pivot upon which the yoke rocks when the back is tilted. To control the tilting ac tion of the back and return the latter to ver tical or substantially vertical position I providejthe usual coil s ring'37 encircling the tension adjusting roc 38. One end of this rod is threaded to receive the handle 39 to vary 'the spring tension, and carried at the other end of the rod rs a curved plate 40 adapted to engage an'upwardlydirectedV hook tlformed as a part oftheextension' of the arms-2Q Overlying the plate QO-and acting as an abutment for one end ofthe coil spring 37 is asubstantially triangular shield or guard-42, having one of itsarms or walls" perforated to permit the rod 38 to extend" The :rod carries a rivet or head 43 at its end adjacent the plate'dO, said therethrough.

headengaging the plate,

" It will be noted that by the interengaga ment of the plate 40 with the hook l'a firm anchorage forthe spring is provided, and by forming thehook as '2L part of the back carrying arms simplicity and economy of [construction are'attainedu To varythe tenslon' of the spring 37, the handle 39 is rotated 1 whereby the spring is "compressed "to a V greater or lessdegree between' thehandle 39' V V and the guard 42." 'It' is desirable to interpose a Washer 44, preferably -of cup shape,

between the outer end of spring 37'Vand'the handle 89 so thatfthe handle may contact with this 'was'herand actthroughthe latter I claim:'-' 1. In a chair iron, the combination with aback, of clamping jawsengaging said '7 back, wedges to engage saldback, and means 7 for operatlng said wedges to" vary the clamp lng act onof'the jaws on'the back; a

2. In a chalr Iron, the combination with-a;

back, of clamping jaws to'engageone face;

of the back, wedges to engage the opposite face of theback, and means to move the wedges toward and from.-e ach other to vary the clamping actionof the jaws on the back.

3. In a chair iron, the combination witha to engage one'face of the back,' wedges to jaws on the "back. i V V 4." In a chair iron, the combination wit'h a back carrying a'substantially concave-ton l V vex plate, of clamp ng jaws having portions;

to engagethe concave'jface of said plate, f

said clamping jaws and one face of each of said Wedges, a support with which the opposite faces of said wedges are adapted to engage, and means for operating said wedges to Vary the clamping action of the jaws on the plate.

6. In a chair iron, the combination with a pair of pivotally supported clamping jaws,

of wedges therebetween, a back having one face designed to be engaged by said jaws and its other face engaged by said wedges, and means for operating said wedges and retaining said aws in pivotally adjusted position.

7. In a chair iron, the combination with an arched support, of a pair of clamping jaws pivotally supported thereby, a back carrying a concavo-convex plate the concave face of which is adapted to be engaged by said clamping jaws, a pair of double faced wedges between said jaws, one face of each jaw being adapted to engage the convex face of the plate and the other jaw face being adapted to engage the said arched support, and means whereby said wedges may be moved along the faces they engage and said jaws locked in adjusted position.

8. In a chair iron, the combination with a support having an arched serrated surface, of a pair of clamping jaws pivoted to said support and having hooked edges, a back carrying a concavo-convex plate the concave face of which is adapted to be engaged by the hooked edges of said jaws, a pair of double faced wedges between said aws, one face of each wedge adapted to engage the convex surface of the plate and the other face of each jaw adapted to engage the said arched serrated surface, and a spindle bearing in the walls of said jaws and passing through said wedges and designed to operate the latter to vary the clamping action of the jaws on the plate.

In testimony whereof I haveaflixed my signature.

HOWARD Gr. HUN N. 

